JP2013099527A - Tennis racket fitting method, fitting program, and analyzing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fitting method for analyzing a swing in which impact with a ball is reflected, thereby selecting a tennis racket that is suited to a player, and to provide a fitting program and an analyzing apparatus.SOLUTION: At least a swing is made by a user with a reference racket to hit a tennis ball, the variation of at least one of the acceleration and angular velocity of a reference tennis racket per at least a time instant from when the swing starts to ends, is calculated to obtain a reference value, at least a swing is made with at least an evaluation target tennis racket to hit a tennis ball, the variation of at least one of the acceleration and angular velocity of the evaluation target racket per at least part of a time instant from when the swing starts to ends, is calculated to obtain a measured value, and a tennis racket is selected based on the reference value and the measured value.

Description

  The present invention relates to a tennis racket fitting method, a fitting program, and an analysis apparatus.

  The tennis racket swing varies from player to player and is also affected by the specifications of the tennis racket. For example, when trying to obtain a high-speed hitting ball with a racket with a small coefficient of restitution, the player will be forced, while when trying to control the hitting speed with a racket with a too large coefficient of restitution, the player's hand will loosen. Therefore, the matching between the player and the racket is important. For this purpose, it is necessary to analyze an appropriate swing, and the appropriate swing analysis can contribute to improvement of the skill of the player. The swing analysis can also contribute to the research and development of tennis rackets, and thereby contribute to the promotion of racket sales.

  Various studies have been made on the analysis of such a swing. For example, in Patent Document 1, a swing is photographed by three high-speed cameras, and the behavior of the racket is analyzed based on the obtained image. An apparatus is disclosed.

  Patent Document 2 discloses a swing speed measuring method, and in this method, a magnet is attached to the tip of a racket. And a swing speed can be calculated because a sensor detects passage of a magnet.

  Further, Patent Document 3 discloses a method in which a swing is analyzed using a three-axis acceleration sensor and a three-axis gyro sensor.

JP 2002-126147 A JP 2006-263340 A JP 2009-125499 A

  However, Patent Documents 1 and 3 disclose the swing analysis but do not describe the tennis racket fitting. In Patent Document 2, an appropriate racket is selected by analyzing the swing of the racket. However, since only the swing is analyzed without hitting the ball, a racket suitable for actual hitting is selected. It cannot be selected properly.

  The present invention has been made to solve the above-described problem, and a tennis racket fitting method capable of selecting a tennis racket suitable for a player by analyzing a swing reflecting an actual ball hit. An object of the present invention is to provide a fitting program and an analysis apparatus.

  The tennis racket fitting method according to the present invention includes a first step of preparing a plurality of test tennis rackets each defining at least one type of racket characteristic that affects a swing when a ball is hit, A reference tennis racket is swung at least once to hit a tennis ball, and at least one transition of the position, velocity, acceleration and angular velocity of the reference tennis racket in at least a part of the period from the start to the end of the swing A second step of measuring the measured value, obtaining a measured value, a third step of calculating at least one evaluation index for swing evaluation in the reference tennis racket based on the measured value, and at least one of the evaluation index The tennis racket that can improve the There have, a, a fourth step of selecting from among said plurality of test tennis racket.

  In the fitting method, after the fourth step, the user is caused to swing the selected tennis racket at least once in order to hit a tennis ball, and at least a part of the swing from the start to the end of the swing is performed. A fifth step of measuring at least one transition of the position, velocity, acceleration, and angular velocity of the selected tennis racket in the section and obtaining a measurement value; and a swing in the selected tennis racket based on the measurement value A sixth step of calculating at least one evaluation index to be evaluated, and a tennis racket capable of improving at least one of the evaluation indices is selected from the plurality of test tennis rackets based on the racket characteristics And the seventh step can be repeated at least once.

  In the fitting method, the racket characteristic may be at least one of the weight, face area, maximum frame thickness, minimum frame thickness, flex, total length, number of main strings, and number of cross slings of each test tennis racket. .

  In the fitting method, the racket characteristics are defined using at least one of the weight, face area, maximum frame thickness, minimum frame thickness, flex, total length, number of main strings, and number of cross slings of each test tennis racket. Can be a numerical value.

    In the fitting method, one of the racket characteristics may be a flight characteristic that is quantified using at least the face area so as to reflect a flight distance of the ball.

  In the above-described fitting method, one of the racket characteristics may be a ball holding characteristic that is quantified by using at least the flex so as to reflect the appropriate timing of ball separation.

  In the above-described fitting method, one of the racket characteristics can be a response characteristic quantified using at least the maximum thickness so as to reflect the appropriateness of impact at the time of impact.

  In the fitting method, in the second step, the test tennis racket is swung a plurality of times to obtain a plurality of measured values, and in the third step, the plurality of measured values are calculated. The evaluation index can be calculated by averaging the evaluation indices.

  A tennis racquet fitting program according to the present invention is a first step of storing in a computer information related to a plurality of test tennis racquets each defining at least one type of racket characteristic that affects a swing when a ball is hit. When the user swings at least once using the tennis racket selected for hitting the tennis ball, the selected value measured in at least a part of the period from the start to the end of the swing is used. A second step of accepting at least one transition of the position, velocity, acceleration and angular velocity of the tennis racket as a measured value, and at least one evaluation index for evaluating a swing in the reference tennis racket based on the measured value. A third step of calculating and the evaluation index Tennis racket capable of improving one even without, on the basis of the racquet characteristics, and a, a fourth step of selecting from among said plurality of test tennis racket.

  In the fitting program, after the fourth step, when the user swings at least once using the selected tennis racket to hit a tennis ball, from the start to the end of the swing. A fifth step of accepting at least one transition of the position, velocity, acceleration and angular velocity of the reference tennis racket measured in at least a section as a measured value; and a swing in the reference tennis racket based on the measured value A sixth step of calculating at least one evaluation index to be evaluated, and a tennis racket capable of improving at least one of the evaluation indices is selected from the plurality of test tennis rackets based on the racket characteristics And the seventh step can be repeated at least once .

  In the fitting program, the racket characteristic may be at least one of the weight, face area, maximum frame thickness, minimum frame thickness, flex, total length, number of main strings, and number of cross slings of each test tennis racket. .

  In the fitting program, the racket characteristics are defined using at least one of the weight, face area, maximum frame thickness, minimum frame thickness, flex, total length, number of main strings, and number of cross slings of each test tennis racket. Can be a numerical value.

  In the fitting program, one of the racket characteristics may be a flight characteristic that is quantified using at least the face area so as to reflect a flight distance of the ball.

  In the above-described fitting program, one of the racket characteristics may be a ball sticking characteristic that is quantified using at least the flex so as to reflect the appropriate timing of the ball separation.

  In the fitting program, one of the racket characteristics may be a response characteristic that is quantified using at least the maximum thickness so as to reflect the appropriateness of the impact feeling at the time of impact.

  In the fitting program, in the second step, a plurality of measured values obtained from a plurality of swings by the test tennis racket are received, and in the third step, calculated from the plurality of measured values. The evaluation index can be calculated by averaging the evaluation indices.

  The tennis racket fitting analyzer according to the present invention is a first memory storing information on a plurality of test tennis rackets each defining at least one type of racket characteristic that affects a swing when a ball is hit. And the reference tennis racket measured at least in a section from the start to the end of the swing when the user swings at least once using the reference tennis racket to hit the tennis ball A second storage unit that stores at least one transition of the position, velocity, acceleration, and angular velocity as a measurement value, and at least one evaluation index that is used to evaluate a swing in the reference tennis racket based on the measurement value And a tennis racket capable of improving at least one of the evaluation indices The door, on the basis of the racquet characteristics, and a, a racket selection unit for selecting from said plurality of test tennis racket.

  According to the present invention, at least one type of racket characteristic that affects the swing when a ball is hit is defined for a plurality of test tennis rackets. Further, an evaluation index for evaluating the swing is calculated from the measured value measured when the racket is tried, and the racket is evaluated. A racket that can improve the evaluation index is selected from a plurality of test tennis rackets based on the racket characteristics. Therefore, when fitting the racket, the racket to be tried next is selected based on the racket characteristics, so that it is possible to reach a racket suitable for the user with fewer trials compared to a case where a plurality of rackets are simply tried. Therefore, efficient fitting is possible.

It is a block diagram showing a schematic structure of a fitting system concerning one embodiment of the present invention. It is a figure which shows schematic structure of a measurement device. It is the perspective view in which the tennis court was shown. It is a flowchart which shows a measurement process. It is the front view by which the tennis racket used for the measurement of a racket angular velocity was shown with the tennis ball. It is a flowchart which shows the procedure of fitting. It is a correlation diagram which shows the relationship between a racket characteristic and actual hitting. It is a graph shown by an output part. It is a graph which shows an example of fitting. It is a graph which shows an example of fitting.

  Hereinafter, a tennis racket fitting system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of the fitting system.

<1. Overview of the fitting system>
As shown in FIG. 1, the tennis racket fitting system according to the present embodiment evaluates a tennis racket swung by a user and selects a tennis racket suitable for the user, that is, fitting a tennis racket. The measuring device 1 for measuring the swing and the analyzer 2 for analyzing the measured value sent from the measuring device 1 are provided. These will be described in detail below.

<1-1. Measuring device>
First, the measuring device 1 will be described with reference to FIG. As shown in FIG. 2, the measurement device 1 includes a sensor unit 11 attached to the tennis racket 10 and a communication unit 12 for transmitting measurement data measured by the sensor unit 11 to the analyzer 2. Yes. The tennis racket 10 used here is a general one, but has a head 103 in which a gut 101 is stretched vertically and horizontally to form a face 102, and a pair of left and right throats from one end of the head 103. 104 extends and is connected to a single shaft 105. The shaft 105 is connected to a grip 106 held by a player (user).

  The sensor unit 11 of the measuring device 1 is attached to the end of the grip 106 so as not to hinder the swing, and the communication unit 12 is attached to the upper arm 502 of the hand 501 that holds the grip 106 (in the example of FIG. 2). right hand). The sensor unit 11 includes a three-axis acceleration sensor 111 and a three-axis gyro sensor 112, and each measures acceleration and angular velocity at relative coordinates (x, y, z) with the racket 10 as a reference. Here, the relative coordinates will be described. The longitudinal direction of the shaft 105 of the racket 10 coincides with the y-axis direction. The direction of the y axis is also parallel to the face 102. The direction from the head 103 toward the grip 106 is the positive direction of the y axis. The direction of the z axis is also parallel to the face 102, but the z axis is orthogonal to the y axis. That is, when the face 102 shown in FIG. 2 is regarded as a clock face, the direction from the 3 o'clock position to the 9 o'clock position is the positive z-axis direction. Although not shown in FIG. 2, the direction of the x axis is perpendicular to both the y axis and the z axis and is perpendicular to the face 102. That is, the direction from the back side to the front side in the thickness direction of the head 103 is the positive direction of the x axis. The front side is the side in contact with the tennis ball during the forehand stroke. The x-axis, y-axis, and z-axis defined in this way are axes based on the racket 10, and the coordinates (x, y, z) are coordinates based on the racket 10. Therefore, the x-axis, y-axis, and z-axis directions vary according to the attitude of the racket 10.

  By the way, in order to analyze the swing of the tennis racket 10 for sending the ball to the opponent team, the moving speed of the racket 10 needs to be based on a fixed ground and space such as a tennis court. . That is, the moving speed of the racket should be based on the absolute coordinates based on the fixed ground and space, not the relative coordinates based on the displaced racket 10 itself. Therefore, in this embodiment, absolute coordinates based on the tennis court are also defined. FIG. 3 is a perspective view showing a tennis court 70 in which the system of FIG. 1 is used. FIG. 3 shows a player 50 performing a swing. The player 50 is right-handed and holds the racket 10 with the right hand 501.

  As shown in FIG. 3, the direction of the side line 71 of the tennis court 70 coincides with the direction of the X axis. The direction from the player's 72 to the opponent's 73 for the player 50 is the positive direction of the X axis. The direction of the end line 74 of the tennis court 70 coincides with the direction of the Y axis, and the direction from right to left for the player 50 facing the opponent team 73 is the positive direction of the Y axis. The direction of the Z axis is the vertical direction, and the upward direction is the positive direction of the Z axis. The X axis, the Y axis, and the Z axis are axes based on the tennis court 70. In other words, the X axis, the Y axis, and the Z axis are axes based on the ground, and are absolute coordinate axes. The (X, Y, Z) coordinates defined by this axis are absolute coordinates.

  Returning to FIG. 1 and FIG. 2, the description of the measuring device 1 will be continued. As shown in FIG. 2, the communication unit 12 is fixed to the upper arm 502 by a band 13 so as not to hinder the player's swing. The sensor unit 11 and the communication unit 12 are connected by a cable 14, whereby the communication unit 12 transmits data measured by the triaxial acceleration sensor 111 and the triaxial gyro sensor 112 through the cable 14 to the sensor unit 11. Receive from. The communication unit 12 wirelessly transmits this data to the analyzer 2, but various communication methods can be applied. For example, short-range wireless communication using a so-called Bluetooth (registered trademark) system, UWB (Ultra Wide Band) system, wireless LAN (Local Area Network), or the like can be used. A battery (not shown) for driving the sensor unit 11 and the communication unit 12 is also fixed to the upper arm 502 by the band 13.

<1-2. Analyzer>
Subsequently, the analyzer 2 will be described. The analyzer 2 includes an output unit 21, an input unit 22, a storage unit 23, a control unit 24, and a communication unit 25. These are connected to each other via a bus line 26 and can communicate with each other. In this embodiment, the output part 21 can be comprised with a liquid crystal display, and the screen etc. which are mentioned later are displayed with respect to the operator of a player or an analyzer. The input unit 22 can be configured with a mouse, a keyboard, a touch panel, and the like, and accepts an operation from the user with respect to the analysis device 2.

  The storage unit 23 includes a storage device such as a hard disk, and stores a fitting program 231 and a software management area 232. The software management area 232 is an area used by the fitting program 231. In the software management area 232, a raw data area 2321, a calculation result area 2322, an evaluation area 2323, a test racket area 2324, and the like are secured. The role of each region 2321 to 2324 will be described later. Note that the fitting program is stored in the storage unit 23 in advance, or is stored in a computer-readable storage medium 20 such as a magneto-optical disk, a CD-ROM, a DVD-ROM, a Blu-ray disk, or a USB memory. It can also be executed by the control unit 24 by installing.

  Moreover, the control part 24 can be comprised from CPU, ROM, RAM, etc. The control unit 24 reads and executes the fitting program 231 stored in the storage unit 23 to virtually operate as the calculation unit 241, the index comparison unit 242, and the racket selection unit 243 as illustrated in FIG. To do. The operation of each unit 241 to 243 will be described later.

  The communication unit 25 also functions as an interface for receiving data from an external storage device such as a USB memory, in addition to receiving data from the communication unit 12 of the measurement device 1. In addition, a printer, a plotter, or the like can be connected as necessary.

<2. Tennis racket fitting>
Next, tennis racket fitting using the above-described measuring device 1 and analyzer 2 will be described. The fitting according to this embodiment includes three steps. That is, a swing measurement step of measuring the acceleration and angular velocity of the racket 10 by the measurement device 1, a calculation step of calculating a swing evaluation index by the analyzer 2 based on the measured acceleration and angular velocity, and a calculated evaluation index 3 is a determination process for determining the fitting based on the above. Hereinafter, these steps will be described in order.

<2-1. Swing measurement process>
FIG. 4 is a flowchart showing an example of a swing measurement process. First, a start button or the like is pressed from the input unit 22 of the analyzer 2, and the player 50 starts swinging the racket 10 (step S1). This swing is not a so-called swing, but hits a tennis ball by a swing. For example, when a tennis ball having a constant direction and a constant speed is supplied to the player's own team 72 of the player 50 by the ball supply device, the player 50 tries to hit it and hit it back to the opponent team 73. The swing at this time is a ground stroke by the forehand with the right hand. A ground stroke means hitting a tennis ball once bounced on the ground of a tennis court. If the hit tennis ball does not enter the opponent 73, the swing is not subject to further analysis. Further, even when the hit tennis ball enters the opponent's team 73, if it is a clear miss shot, the swing is not subject to subsequent analysis.

  While the swing is performed, the triaxial acceleration sensor 111 and the triaxial gyro sensor 112 measure the acceleration and the angular velocity at each time (step S2). More specifically, the triaxial acceleration sensor 111 has a predetermined sampling interval and grip accelerations A (gx) and A (gy) in the relative x-axis direction, the relative y-axis direction, and the relative z-axis direction. And A (gz). Further, the triaxial gyro sensor 112 has a grip angular velocity ω (gx), ω (gy), and ω around the relative x axis, the relative y axis, and the relative z axis at each time. (Gz) is measured. Although the predetermined sampling interval is not particularly limited, for example, data can be obtained every 1/1000 to 1/500 seconds. When the swing ends (YES in step S3), the measurement ends. Although the swing can be performed any number of times, it is preferable to measure, for example, about 3 to 10 swings in consideration of the number of times until the swing is stabilized. The grip accelerations A (gx), A (gy) and A (gz) and grip angular velocities ω (gx), ω (gy) and ω (gz) measured in this way are transmitted from the communication unit 12 to the analyzer 2. It is transmitted to the communication unit 25 (step S4). Then, the transmitted data is stored in the raw data area 2321 of the storage unit 23 by the control unit 24 (step S5). The end of the measurement can be operated from the analyzer 2 by the input unit 22, for example. At this time, measurement data can be transmitted in real time simultaneously with the measurement.

  <2-2. Evaluation index calculation process>

  Subsequently, the calculation unit 241 of the control unit 24 includes the grip accelerations A (gx), A (gy) and A (gz) and the grip angular velocities ω (gx), ω () stored in the raw data area 2321 of the storage unit 23. A swing evaluation index is calculated using all or part of the data of gy) and ω (gz) (step S21). Examples of the evaluation index include grip acceleration, grip speed, head speed, head acceleration, head speed component ratio, swing path, and racket angular velocity.

  In calculating these evaluation indexes, it becomes a problem as to which data at the time from the start to the end of the swing should be used. That is, the grip accelerations A (gx), A (gy) and A (gz) and the grip angular velocities ω (gx), ω (gy) and ω (gz) are obtained for each time. A time suitable for determining matching between the player 50 and the racket 10 is selected. Here, as an example of a time suitable for determining the matching, when the head speed is used, a time when the head speed is maximum can be given. The head speed gradually increases after the start of the swing, but the head 103 decelerates rapidly due to the impact with the tennis ball. The time immediately before this deceleration occurs is the time when the head speed becomes maximum. Hereinafter, each evaluation index including the head speed will be described.

[Head speed]
The head speed is the data of grip acceleration A (gx), A (gy) and A (gz) for each time of the relative coordinate axes x, y and z; the grip angular velocity ω (gx for each time of the relative coordinate axes x, y and z ), Ω (gy) and ω (gz) data; and the racket length. First, the calculation unit 241 calculates grip speeds V (gX), V (gY), and V (gZ) for each time in the XYZ absolute coordinate system using the above-described mathematical formula. On the other hand, the calculation unit 241 calculates the rotation matrix RM from the quaternion described above. The computing unit 241 further calculates a velocity vector Vr by rotation for each time in the XYZ absolute coordinate system based on the following mathematical formula.
Vr = cross (ω, tV) * RM
In this equation, cross (ω, tV) is the outer product of the angular velocity vector ω and the racket length vector tV for each time in the xyz relative coordinate system.

Head speeds V (hx), V (hy), and V (hz) for each time of the absolute coordinate axes x, y, and z are calculated by the calculation unit 241 according to the following formula.
V (hX) = V (gX) + Vr (X)
V (hY) = V (gY) + Vr (Y)
V (hZ) = V (gZ) + Vr (Z)

Subsequently, the calculation unit 241 calculates the head speed V (h) at each time in the XYZ absolute coordinate system from the head speeds V (hX), V (hY), and V (hZ) at each time in the XYZ absolute coordinate system. ) Is calculated. The calculation is performed based on the following mathematical formula.
V (h) = SQRT (V (hX) ² + V (hY) ² + V (hZ) ² )
The head speed V (h) for each time is stored in the calculation result area 2322.

  Then, the computing unit 241 selects the head speed VV (h) immediately before the impact (immediately before deceleration) from the magnitude V (h) of the head speed at each time as the maximum head speed VV (h). The computing unit 241 evaluates the head speed V (hX), V (hY) and V (hZ) for each time, the magnitude V (h) of the head speed for each time, and the maximum head speed VV (h). Stored in the evaluation area 2322 as an index. Although the head speed gradually increases after the start of the swing motion, the head speed is rapidly decelerated due to the impact of the tennis racket 10 and the tennis ball. Therefore, the time at which the maximum head speed V (h) is obtained is the time immediately before the impact, and is considered a time suitable for determining the compatibility between the player 50 and the racket 10. The head speed in the absolute coordinate system is calculated based on the measured values of the grip speed and the grip angular speed in the relative coordinate system. The sensor unit 11 is attached to the tip of the head 103 to measure the head acceleration in the relative coordinate system. The head speed in the absolute coordinate system can be obtained from the value obtained by converting the head acceleration into the absolute coordinate system.

[Head acceleration]
The head acceleration in the XYZ absolute coordinate system is calculated based on the head velocities V (hX), V (hY), and V (hZ) in the XYZ absolute coordinate system. More specifically, the calculation unit 241 differentiates V (hX), V (hY), and V (hZ), which are the X-axis, Y-axis, and Z-axis components of the head speed at each time, by time, respectively. Then, A (hX), A (hY), and A (hZ), which are X-axis, Y-axis, and Z-axis components of the head acceleration at each time, are calculated.

Subsequently, the calculation unit 241 calculates the head acceleration magnitude A (h) at each time in the XYZ absolute coordinate system from the head accelerations A (hX), A (hY), and A (hZ) at each time in the XYZ absolute coordinate system. ) Is calculated. The calculation is performed based on the following mathematical formula.
A (h) = SQRT (A (h (hX) ² + A (hY) ² + A (hZ) ² )

  Then, the calculation unit 241 selects the head acceleration AA (h) immediately before impact (immediately before deceleration) from the head acceleration magnitude A (h) at each time. Then, the calculation unit 241 evaluates the head acceleration A (hX), A (hY) and A (hZ) for each time, the magnitude A (h) of the head acceleration for each time, and the maximum head acceleration AA (h). Stored in the evaluation area 2322 as an index. The head acceleration in the absolute coordinate system is calculated based on the measured values of the grip speed and the grip angular speed in the relative coordinate system. The sensor unit 11 is attached to the tip of the head 103 to measure the head acceleration in the relative coordinate system. The head acceleration can be converted into an absolute coordinate system.

[Head speed component ratio]
The head velocity component ratio I in the XYZ absolute coordinate system is the grip accelerations A (gx), A (gy) and A (gz) in the xyz relative coordinate system, and the grip angular velocities ω (gx), ω (gy) in the xyz relative coordinate axis system. And ω (gz), and racket length data. Specifically, first, the computing unit 241 calculates V (hX) and V (hZ), which are the X-axis and Z-axis components of the head speed at each time in the XYZ absolute coordinate system, using the above-described mathematical formula. Subsequently, the calculation unit 241 calculates the head speed component ratio I for each time in the XYZ absolute coordinate system based on the following mathematical formula.
I = V (hZ) / V (hX)

  Then, the calculation unit 241 selects, as the maximum head speed component ratio II, the one immediately before impact (immediately before deceleration) from the head speed component ratio I at each time. Then, the calculation unit 241 stores the head speed component ratio I and the maximum head acceleration II for each time in the evaluation area 2322 as evaluation indexes. The head speed component ratio is calculated based on the measured values of the grip speed and the grip angular speed in the relative coordinate system. The sensor unit 11 is attached to the tip of the head 103 to measure the head acceleration in the relative coordinate system. The head speed component ratio I can also be obtained from the value obtained by converting the head acceleration into the absolute coordinate system.

[Grip speed]
The grip speed in the XYZ absolute coordinate system is calculated based on data of grip accelerations A (gX), A (gY), and A (gZ) in the XYZ absolute coordinate system. More specifically, the calculation unit 241 calculates V (gX), V (gY), and V (gZ), which are the X-axis, Y-axis, and Z-axis components of the grip speed for each time, based on the following formula. Is done.
ΔV (gX) = A (gX) * ΔT
ΔV (gY) = A (gY) * ΔT
ΔV (gZ) = A (gZ) * ΔT
In the above formula, ΔT is a minute time (the above-described sampling interval), and ΔV (gX), ΔV (gY), and ΔV (gZ) are V (gX), V (gY), and V (in the minute time ΔT. gZ) increments. The value of ΔT is appropriately input to the analyzer 2 by the operator.

Subsequently, the calculation unit 241 increases the grip speed V (g) for each time in the XYZ absolute coordinate system from the grip speeds V (gX), V (gY), and V (gZ) for each time in the XYZ absolute coordinate system. Is calculated. The calculation is performed based on the following mathematical formula.
V (g) = SQRT (V (gX) ² + V (gY) ² + V (gZ) ² )

  And the calculating part 241 selects the thing immediately before an impact (immediately before decelerating) from the magnitude | size V (g) of the grip speed for every time as the maximum grip speed VV (g). Then, the calculation unit 241 evaluates the grip speed V (gX), V (gY), and V (gZ) for each time, the magnitude V (g) of the grip speed for each time, and the maximum grip speed VV (g). Stored in the evaluation area 2322 as an index. A large maximum grip speed VV (g) means that the arm 50 of the player 50 and the hand are not loose. Further, the fact that the maximum grip speed VV (g) is large also means that the racket 12 matches the player 50.

[Grip acceleration]
The grip acceleration in the XYZ absolute coordinate system includes grip accelerations A (gx), A (gy) and A (gz) in the xyz relative coordinate system, and grip angular velocities ω (gx), ω (gy) and ω in the xyz relative coordinate system. It is calculated based on the data (gz). More specifically, the calculation unit 241 causes the grip accelerations A (gx), A (gy), and A (gz) at each time to be determined as the grip angular velocities ω (gx), ω (gy), and ω (gz) at each time. ) Is converted into A (gX), A (gY), and A (gZ), which are X-axis, Y-axis, and Z-axis components of grip acceleration at each time. The quaternion used for conversion is represented by the following mathematical formula.
Q = [cos (θ); ω (gx) / θ * sin (θ / 2), ω (gy) / θ * sin (θ / 2), ω (gz) / θ * sin (θ / 2)]
R = [cos (θ); -ω (gx) / θ * sin (θ / 2), -ω (gy) / θ * sin (θ / 2), -ω (gz) / θ * sin (θ / 2)]
Θ in the above formula is obtained by the following formula.
θ = SQRT (ω (gx) ² + ω (gy) ² + ω (gz) ² )

Subsequently, the calculation unit 241 calculates the grip acceleration magnitude A (g) for each time in the XYZ absolute coordinate system from the grip accelerations A (gX), A (gY) and A (gZ) for each time in the XYZ absolute coordinate system. ) Is calculated. The calculation is performed based on the following mathematical formula.
A (g) = SQRT (A (gx) ² + A (gy) ² + A (gz) ² )

  Then, the computing unit 241 selects the grip acceleration magnitude A (g) at each time immediately before the impact (immediately before deceleration) as the maximum grip acceleration AA (g). Then, the calculation unit 241 evaluates grip accelerations A (gX), A (gY), and A (gZ) for each time, a grip acceleration magnitude A (g) for each time, and a maximum grip acceleration AA (g). Stored in the evaluation area 2322 as an index. A large maximum grip acceleration AA (g) means that the arm 48 of the player 48 and the looseness of the hand are small, and that the tennis ball can be hit hard. In addition, a large maximum grip acceleration AA (g) also means that the racket 10 matches the player 50.

[Swing trajectory]
The swing trajectory in the XYZ absolute coordinate system includes grip accelerations A (gx), A (gy) and A (gz) in the xyz relative coordinate system, and grip angular velocities ω (gx), ω (gy) and ω (in the xyz relative coordinate axis system. gz) and the racket length data. Specifically, first, the calculation unit 241 calculates the grip speeds V (gX), V (gY), and V (gZ) for each time in the XYZ absolute coordinate system using the above-described mathematical formula. Subsequently, the calculation unit 241 calculates the X-axis, Y-axis, and Z-axis components of the position of the grip 11 for each time from the grip speeds V (gX), V (gY), and V (gZ) based on the following formula. P (gX), P (gY) and P (gZ) are calculated.
ΔP (gX) = V (gX) * ΔT
ΔP (gY) = V (gY) * ΔT
ΔP (gZ) = V (gZ) * ΔT
In the above formula, ΔT is a minute time (the above-described sampling interval), and ΔP (gX), ΔP (gY), and ΔP (gZ) are P (gX), P (gY), and P (in the minute time ΔT. gZ) increments.

Further, the calculation unit 241 calculates the relative position P (h) of the top of the head 103 for each time with respect to the grip 106 by the following mathematical formula.
P (h) = tV * RM
In the above formula, tV is the aforementioned racket length vector, and RM is the aforementioned rotation matrix. The calculation unit 241 calculates absolute coordinates (Xt, Yt, Zt) of the top of the head 103 for each time according to the following mathematical formula, and stores them in the evaluation area 2322 as evaluation indexes. The absolute coordinates (Xt, Yt, Zt) for each time mean the trajectory of the racket 10.
(Xt, Yt, Zt) = P (g) + P (h)

The computing unit 241 calculates the movement distance J _X of the head 103 in the absolute coordinate axis X direction from time to to t by the following mathematical formula.
J _X = (Xt−Xto)
The calculation unit 241 calculates the movement distance J _Y of the head 103 in the absolute coordinate axis Y direction from time to to t by the following mathematical formula.
J _Y = (Yt−Yto)
The movement distances J _X and J _Y are stored in the evaluation area 2322 as evaluation indexes.

The travel distances J _X and J _Y in various time zones can be calculated. For example, the movement distances J _X and J _Y between t seconds before the impact and the impact can be calculated. Also, the movement distances J _X and J _Y between the impact and t seconds after the impact can be calculated.

  The trajectory of the racket 12 is determined from the movement distances Jx and Jy. Based on this trajectory, it can be determined whether or not the racket 10 is suitable for the player 50. For example, an ideal trajectory is set, and a racket close to this trajectory can be determined as the racket 10 that matches the player 50. As an ideal trajectory, for example, when a racket with good matching with the player is swung, it swings forward greatly or the swing angle decreases.

  Since the swing locus can be calculated based on the grip speed, the triaxial acceleration sensor 111 and the triaxial gyro sensor 112 do not need to be attached to the head 103.

[Racquet angular velocity]
The racket angular velocity in the xyz relative coordinate system is a grip angular velocity ω (gy) around the y axis, which is a measurement value of the three-axis gyro sensor 112.
FIG. 5 shows the tennis racket 10 in the sampling process. FIG. 5 shows the head 103 viewed along the direction of the relative coordinate axis y. FIG. 5 also shows a tennis ball 90 immediately before impacting the racket 10. In this drawing, an arrow A indicates the rotation direction of the head 103. The angular velocity of this rotation is the aforementioned grip angular velocity ω (gy). The grip angular velocity ω (gy) for each time is stored in the evaluation area 2322 as a racket angular velocity for each time, which is an evaluation index. In addition, the calculation unit 241 selects the grip angular velocity ω (gy) immediately before the impact (immediately before deceleration) from the grip angular velocity ω (gy) at each time as the maximum grip angular velocity ωω, and stores it in the evaluation area 2322 as an evaluation index.

  A positive value of the grip angular velocity ω (gy) means a swing type in which the tennis ball 90 is hit while the face 102 is closed. The negative value of the grip angular velocity ω (gy) means that it is a swing type that hits the tennis ball 90 while opening the face 102. For example, if the grip angular velocity is relatively large, it can be determined that the racket does not match because there are many surface operations. Alternatively, if there is a large variation in grip angular velocity when swinging a plurality of times, it can be determined that the racket does not match because the surface operation is not constant. Thus, the player 50 can select the racket 10 suitable for his / her swing type.

  Each evaluation index described above can be calculated based on one measurement value. For example, a plurality of swings are performed, a plurality of evaluation indices are calculated from the measurement values in each swing, and the averages are calculated. Can also be used as an evaluation index. In this case, the average value of these is calculated by the calculation unit 241.

<2-3. Fitting judgment process>
Subsequently, the determination process leading to the selection of the racket will be described with reference to FIG. 6 including the two processes so far. FIG. 6 is a flowchart showing a procedure for fitting determination. First, a reference tennis racket is prepared as a reference for evaluation. This tennis racket can be, for example, the player's own tennis racket. Next, using this tennis rat, acceleration and angular acceleration are measured according to the two steps described above (step S10), and the calculation unit 241 calculates the evaluation index described above from here (step S11). Any of the above-described evaluation indices may be used, and all evaluation indices may be used, or some of them may be used. The evaluation index of the reference tennis racket thus calculated is referred to as a reference evaluation index. Subsequently, a test tennis racket for fitting is prepared, and measurement is performed using the tennis racket (step S12), and an evaluation index is calculated based on the measured value (step S13). This is called a test evaluation index. These reference evaluation index and test evaluation index are stored in the evaluation area 2323 of the storage unit. Subsequently, the index comparison unit 2323 compares the reference evaluation index stored in the evaluation area 2323 with the test evaluation index. If the test evaluation index is larger (YES in step S14), the test tennis racket is used. The recommended tennis racket is determined and output to the output unit 21 (step S15). Although the output method is not particularly limited, for example, display on a display, output by a printer, or the like is performed. As described above, each of the evaluation indices related to speed and acceleration is larger as it matches the player. Therefore, a racket having a larger evaluation index than the player's own racket is determined to be a racket that matches the player. can do. The other evaluation indexes are as described above.

  On the other hand, if the reference evaluation index is larger (NO in step S14), another test tennis racket is selected, the measurement of the swing using the test racket and the calculation of the evaluation index are repeated, and is higher than the reference evaluation index. Repeat until. However, even if the reference evaluation index is smaller, it is possible to try another test tennis racket and search for a better test tennis racket instead of ending the fitting.

<3. Racket selection>
By the way, in the fitting determination step, a tennis racket for testing is selected. This selection can be performed by various methods. For example, the prepared rackets may be tried in order, but there is an efficient problem. Therefore, the racket characteristics of each test tennis racket can be set, and the racket can be selected based on the racket characteristics while considering the evaluation index. Hereinafter, this method will be described.

<3-1. Racket characteristics>
There are various racket characteristics that affect the swing, and examples thereof include “flying”, “ball-like”, and “response”. However, other racket characteristics can be considered. “Flying” is a racket characteristic indicating the appropriateness of the repulsive force and the flying distance, and “Ball mochi” is a racket characteristic indicating the appropriateness of the timing of ball separation. “Hand response” is a racket characteristic indicating the weight of hit feeling and the appropriateness of impact. It has been found that increasing or decreasing these racket characteristics has the following effects on the player.

Therefore, if these racket characteristics are digitized, it is considered that the properties of the racket can be easily expressed, so that the racket can be selected efficiently. Here, in consideration of the properties of each racket characteristic, three index values obtained by quantifying the racket characteristic are set as follows. These index values are set using racket specifications.
(1) Jump index value
The flying index value is a numerical value of the racket characteristics indicating the appropriateness of repulsive force and flying distance. From the racket specs, those that have a positive effect on the flight are used as numerators, and the flight has a negative effect. I have something as a denominator. In particular, the “face area” that affects the flying is increased by squaring.
(2) Sphere stick index value
The sphere-mochi index value is a numerical value of the racket characteristic that indicates the appropriate timing of sphere separation, and from the racket specs, those that have a positive effect on the sphere-mochi are used as numerators, and those that have a negative effect Is the denominator. In particular, flex that has a negative effect on the sphere has a greater effect by squaring.
(3) Response index value
The response index value is a numerical value of the racket characteristics that indicate the weight of the hit feeling and the appropriateness of the impact feeling. From the racket specs, those that have a positive effect on response are used as numerators, and negative effects are expressed. The denominator is what you give. In particular, the maximum thickness that negatively affects the response is increased by squaring.

  For the above index values, the numerical values calculated based on the above formulas can be used, but if they are used as they are, the numerical values become too large to be used as a material for judgment. It is also possible to multiply the correction coefficient and make a relative value based on the value of a certain racket. Further, the setting of the index value is an example, and it goes without saying that the index value can be set by a mathematical expression other than this.

  Subsequently, the correlation between these index values and actual hits is examined, and the effectiveness of the three racket characteristics set here is examined. First, prepare the following nine tennis rackets. The index value is a relative value when REVOX 4.0 is used as a reference and 10 points are set.

Using these rackets, 20 players made actual hits, and sensory evaluations of actual flight, ball holding, and response were made. Twenty players performed a rally with a swing by stroke, evaluated each racket characteristic in five stages (5 points is the best value), and averaged these to calculate the specific hit. The results are as shown in Table 3 below and FIG.

  According to the graph of FIG. 7, in any racket characteristic, the correlation coefficient is 0.8 or more between the index value and the actual number of hit points, and it was found that the index value of the racket characteristic is effective. The racket characteristic index values shown in Table 2 are stored in the test racket area 2324 of the storage unit 23 of the analyzer 2.

<3-2. Fitting using racket characteristics>
Next, racket fitting is performed using the racket characteristics. Here, fitting is performed using the head speed as an evaluation index. More specifically, the evaluation index is output to a graph as shown in FIG. 8 for evaluation. In this graph, the horizontal axis represents the head speed V (hx) in the X-axis direction at the time when the head speed V (h) is maximum, that is, the flat speed component. The vertical axis represents the head speed V (hZ) in the Z-axis direction at the time when the head speed V (h) is maximum, that is, the spin speed component. The distance L from the origin (0, 0) of the point (V (hX), V (hZ)) on this graph is calculated by the following mathematical formula.
L = SQRT (V (hx) ² + V (hz) ² )
This distance L is the head speed V ′ (h) when the head speed V (hy) in the y-axis direction is assumed to be zero. Although many arcs are drawn in FIG. 8, the center of each arc is the origin (0, 0). The radius of this arc indicates the head speed V ′ (h).

  In FIG. 8, a first point 56, a second point 58, and a third point 60 are shown. The first point 56 is shown as a filled square. The second point 58 is indicated by a filled circle. The third point 60 is indicated by a filled triangle. The first point 56 indicates a point (V (hX), V (hZ)) when the first racket is swung. The second point 58 indicates a point (V (hX), V (hZ)) when the second racket is swung. The third point 60 indicates a point (V (hX), V (hZ)) when the third racket is swung. Hereinafter, two examples of fitting will be described using this graph. Here, the average when each racket is swung five times is calculated as an evaluation index.

  FIG. 9 shows an example of fitting 1. First, the player's own racket is swung and a reference evaluation index is calculated. This player is a man and a senior tennis player. The reference evaluation index calculated at this time is a straight line shown in (i) of FIG. Subsequently, REVOX 4.0 is used as a test tennis racket, and after swinging, a test evaluation index is calculated. The result is a straight line shown in (ii) of FIG. Comparing these indexes, both the flat velocity component and the spin velocity component of the racket (ii) are lower than those of (i). That is, it is considered that the swing speed of the racket has decreased because “flying” is too good. Therefore, it is considered to have a racket with a small index value of “flying” in the racket characteristic.

  Here, in the control unit 24 of the analyzer 2, after the calculation unit 241 calculates the evaluation index, the index comparison unit 242 compares the two evaluation indexes. Then, based on the result, the racket selection unit 243 selects REVOX 2.0 having a jump index value smaller than REVOX 4.0 with reference to Table 2, and displays it on the output unit 21. Thus, when the player makes an actual hit with REVOX 2.0, the result is displayed on the graph. The result is a straight line shown in (iii) of FIG. According to this result, although both the flat velocity component and the spin velocity component are increased, the increase is slight and does not exceed the reference evaluation index. Here, when REVOX 4.0 is compared with REVOX 2.0, “ball stickiness” and “response” are large. Therefore, based on the result of the index comparison unit 242, the racket selection unit 243 reduces the index value. Select a racket with That is, REVOV3.0 is selected.

  Subsequently, when the player makes an actual hit with REVOV3.0, the result is displayed on the graph. The result is a straight line shown in (iv) of FIG. According to this result, both the flat velocity component and the spin velocity component greatly increase and exceed the reference evaluation index. Therefore, finally, REVOV3.0 is recommended.

  Next, FIG. 10 shows an example of the fitting 2. First, the player's own racket is swung and a reference evaluation index is calculated. This player is a woman and an intermediate tennis player. The reference evaluation index calculated at this time is a straight line shown in (i) of FIG. Subsequently, REVOX 4.0 is used as a test tennis racket, and after swinging, a test evaluation index is calculated. The result is a straight line shown in (ii) of FIG. When these indexes are compared, the rack speed of (ii) has an improved spin speed component but a reduced swing speed compared to (i). Since the improvement of the spin speed component shows that the swing is increased, it is necessary to suppress the swing. Therefore, the racket selection unit 243 refers to Table 2, and selects NEOMAX 2000 that suppresses “jump” and raises “ball stickiness”. Thus, when the player makes an actual hit with NEOMAX 2000, the result is displayed on the graph. The result is a straight line shown in (iii) of FIG. From this straight line, the swing up of the swing has decreased, but the swing speed has not increased. Therefore, since there is a possibility that it is pushed by “response” (impact force), the racket selection unit 243 selects REVOV5.0 with reduced “response”. When the player makes an actual hit with NREVOV5.0, the result is displayed on the graph. The result is a straight line shown in (iv) of FIG. According to this graph, it can be seen that the swing speed is higher than the person's racket. Therefore, finally, REVOV5.0 is recommended.

Although there are various setting methods for the selection by the racket selection unit 243, it can be set as follows, for example.

<4. Features>
As described above, according to the present embodiment, at least one type of racket characteristic that affects the swing when a ball is hit is defined for a plurality of test tennis rackets. Further, an evaluation index for evaluating the swing is calculated from the measured value measured when the racket is tried, and the racket is evaluated. A racket that can improve the evaluation index is selected from a plurality of test tennis rackets based on the racket characteristics. Therefore, when fitting the racket, the racket to be tried next is selected based on the racket characteristics, so that it is possible to reach a racket suitable for the user with fewer trials compared to a case where a plurality of rackets are simply tried. Therefore, efficient fitting is possible.

<5. Modification>
The present invention is not limited to the embodiment described above, and various modifications can be made without departing from the spirit of the present invention.

<5-1>
In the above embodiment, “flying”, “ball-like”, and “handling” are adopted as the racket characteristics, but other racket characteristics may be used.
In addition, the racket specs can be used directly. For example, the weight of the racket, the face area, the maximum frame thickness, the minimum frame thickness, the flex, the total length, the number of main strings, the number of cross slings, and the like can be used. Hereinafter, these features will be briefly described.
(i) Weight: The swing speed increases as the weight decreases, and the swing speed decreases as the weight increases. If it becomes lighter, it will fly too much, so it will be suppressed, and conversely the swing speed may become slower.
(ii) Face area: When it becomes larger, it flies, the ball sticks up, and the response decreases.
(iii) Maximum frame thickness: When combined with frame thickness ↓
(iv) Minimum frame thickness: Flying thicker, ball-thickness, and less responsiveness
(v) Flex: When you raise (harden), the flying will rise, and the feeling of the ball will be less comfortable
(vi) Total length: If you make it longer, the flying will go up,
(vii) Number of main strings: When combined with the number of strings ↓
(viii) Number of cross slings: If the number of cross slings is large, the flying and ball stickiness will decrease and the response will increase. As described above, various parameters can be used for the racket characteristics. It is possible to select a suitable racket.

<5-2>
In the above embodiment, the fitting is performed using each evaluation index at the time when the head speed is maximum, but this is merely an example. Therefore, a time other than the time at which the head speed becomes maximum can be used, and an evaluation index other than the head speed can also be used. Examples of other evaluation indices are given below.

(1) Fitting at a speed before and after impact After the start of the swing, the head speed gradually increased, and the head 103 decelerated rapidly due to the impact with the tennis ball, but then the head speed increased again by following the racket. Then slow down. Therefore, in the swing, a peak occurs immediately before the impact with the tennis ball and at the subsequent follow-up. Here, the smaller the difference between the maximum head speed immediately before the impact and the maximum head speed at the time of follow-up, the more the racket is swung through, and it can be said that the racket matches the player. Therefore, this difference can be used as an evaluation index, and a racket that reduces this difference is a recommended racket.

(2) Fitting by acceleration at impact The racket that matches the player has a large acceleration at impact. Therefore, the acceleration during impact can be used as an evaluation index.

(3) Fitting in the time from the start of the swing to the impact The racket that suits the player has a short time from the start of the swing to the impact and stabilizes the timing. Therefore, this time can be used as an evaluation index. That is, a racket that shortens this time is a recommended racket.

<5-3>
In the above embodiment, the swing due to the ground stroke is measured, but it can also be a swing during volley and serve. Volleying refers to hitting a tennis ball hit by an opponent player directly before falling on the ground of a tennis court. “Serve” refers to hitting a tennis ball thrown by a hitting player directly toward an opponent 73 before falling on the ground of a tennis court.

  Further, in both the volley swing and the serve swing, from the measured values by the three-axis acceleration sensor 111 and the three-axis gyro sensor 112, grip acceleration, grip speed, head speed, head acceleration, and head speed component as indices Ratio, swing trajectory, racket angular velocity, etc. can be obtained. The same criteria as the criteria for ground stroke can be adopted as criteria for judging racket fitting for volley and serve.

<5-4>
In the above description, the acceleration and angular velocity of the racket are measured, but the position and velocity of the racket can be measured, and the evaluation index can be calculated from these. Moreover, it is not necessary to use all measured values, and an evaluation index may be calculated using necessary ones.

<5-5>
In the above description, the three-axis acceleration sensor 111 and the three-axis gyro sensor 112 are used for the measurement device 1, but other sensors are used as long as the position, velocity, acceleration, and angular velocity of the racket can be measured. You can also.

<5-6>
In the above embodiment, the data measured by the measuring device 1 is transmitted to the analyzer 2 by wireless communication. However, the data measured by the measuring device 1 is recorded in an external storage device such as a USB memory, and this external Data can also be stored in the storage unit 23 from the storage device via the communication unit 25 of the analyzer 2.

<5-7>
The racket acceleration and angular velocity can be measured by means other than the measuring device described above. For example, it is possible to measure the position, velocity, acceleration, and angular velocity of the racket by photographing the player swinging and performing image processing on the captured moving image.

DESCRIPTION OF SYMBOLS 1 Measuring device 2 Analyzer 23 Storage part 2321 Raw data area (2nd storage part)
2324 Test racket area (first storage)
241 Calculation unit 243 Racket selection unit

Claims (17)

A first step of preparing a plurality of test tennis rackets each defining at least one type of racket characteristic that affects a swing when a ball is hit;
The user is caused to swing the reference tennis racket at least once in order to hit the tennis ball, and at least the position, speed, acceleration and angular velocity of the reference tennis racket in at least a part of the period from the start to the end of the swing. A second step of measuring one transition and obtaining a measured value;
A third step of calculating at least one evaluation index, which is an evaluation of a swing in the reference tennis racket, based on the measured value;
A fourth step of selecting a tennis racket capable of improving at least one of the evaluation indices from the plurality of test tennis rackets based on the racket characteristics;
A tennis racket fitting method. After the fourth step,
The user is caused to swing the selected tennis racket at least once to hit a tennis ball, and the position, speed, and the position of the selected tennis racket in at least a part of the period from the start to the end of the swing. A fifth step of measuring at least one transition of acceleration and angular velocity and obtaining a measurement value;
A sixth step of calculating at least one evaluation index which is an evaluation of a swing in the selected tennis racket based on the measured value;
A seventh step of selecting a tennis racket capable of improving at least one of the evaluation indices from the plurality of test tennis rackets based on the racket characteristics;
The method for fitting a tennis racket according to claim 1, wherein the step is repeated at least once.   The racket characteristic is at least one of the weight, face area, maximum frame thickness, minimum frame thickness, flex, total length, number of main strings, and number of cross slings of each test tennis racket. The tennis racket fitting method described.   The racket characteristic is a numerical value defined using at least one of the weight, face area, maximum frame thickness, minimum frame thickness, flex, total length, number of main strings, and number of cross slings of each test tennis racket. The method for fitting a tennis racket according to claim 1 or 2.   5. The tennis racket fitting method according to claim 4, wherein one of the racket characteristics is a flight characteristic numerically expressed by using at least the face area so as to reflect a flight distance of the ball.   5. The tennis racket fitting method according to claim 4, wherein one of the racket characteristics is a ball holding characteristic that is quantified using at least the flex so as to reflect the appropriate timing of ball separation.   5. The tennis racket fitting method according to claim 4, wherein one of the racket characteristics is a response characteristic quantified by using at least the maximum thickness so as to reflect an appropriate impact feeling at the time of hitting. In the second step, the test tennis racket is swung a plurality of times to obtain a plurality of measured values,
The tennis racket fitting method according to any one of claims 1 to 7, wherein, in the third step, the evaluation index is calculated by averaging the evaluation indices calculated from the plurality of measurement values. On the computer,
A first step of storing information relating to a plurality of test tennis rackets in which at least one type of racket characteristic affecting the swing when the ball is hit is defined;
The position of the reference tennis racket measured in at least a part of the period from the start to the end of the swing when the user swings at least once using the reference tennis racket to hit the tennis ball; A second step of accepting at least one transition of velocity, acceleration and angular velocity as a measured value;
A third step of calculating at least one evaluation index, which is an evaluation of a swing in the reference tennis racket, based on the measured value;
A fourth step of selecting a tennis racket capable of improving at least one of the evaluation indices from the plurality of test tennis rackets based on the racket characteristics;
A tennis racket fitting program. After the fourth step,
When the user swings at least once using the selected tennis racket to hit a tennis ball, the selected is measured in at least a part of the period from the start to the end of the swing A fifth step of accepting at least one transition of the position, velocity, acceleration and angular velocity of the tennis racket as a measurement value;
A sixth step of calculating at least one evaluation index which is an evaluation of a swing in the selected tennis racket based on the measured value;
A seventh step of selecting a tennis racket capable of improving at least one of the evaluation indices from the plurality of test tennis rackets based on the racket characteristics;
The tennis racket fitting program according to claim 9, wherein the above is repeated at least once.   The racket characteristic is at least one of the weight, face area, maximum frame thickness, minimum frame thickness, flex, total length, number of main strings, and number of cross slings of each test tennis racket. The mentioned tennis racket fitting program.   The racket characteristic is a numerical value defined using at least one of the weight, face area, maximum frame thickness, minimum frame thickness, flex, total length, number of main strings, and number of cross slings of each test tennis racket. The tennis racket fitting program according to claim 9 or 10.   The tennis racket fitting program according to claim 12, wherein one of the racket characteristics is a flight characteristic numerically expressed using at least the face area so as to reflect a flight distance of the ball.   The tennis racquet fitting program according to claim 12, wherein one of the racket characteristics is a ball sticky characteristic that is quantified by using at least the flex so as to reflect the appropriate timing of the ball separation.   The tennis racquet fitting program according to claim 12, wherein one of the racket characteristics is a response characteristic quantified by using at least the maximum thickness so as to reflect an appropriate impact feeling at the time of hitting. In the second step, a plurality of measured values obtained from the plurality of swings by the test tennis racket are received,
The tennis racket fitting program according to any one of claims 9 to 15, wherein, in the third step, the evaluation index is calculated by averaging the evaluation indices calculated from the plurality of measurement values. A first storage unit that stores information on a plurality of test tennis rackets in which at least one type of racket characteristic that affects the swing when the ball is hit is defined;
The position of the reference tennis racket measured in at least a part of the period from the start to the end of the swing when the user swings at least once using the reference tennis racket to hit the tennis ball; A second storage unit that stores at least one transition of velocity, acceleration, and angular velocity as a measurement value;
Based on the measured value, a calculation unit that calculates at least one evaluation index that is an evaluation of a swing in the reference tennis racket;
A racket selection unit that selects a tennis racket capable of improving at least one of the evaluation indices from the plurality of test tennis rackets based on the racket characteristics;
An analysis device for tennis racket fittings.